+ better detection of whether a branch is remote tracked
+ instead of git pull --rebase is used git fetch and git rebase
+ added verification whether the remote server is available
+ do a git checkout only if the required branch is not active
+ added support for creating a 'tde' submodules tree using git worktree
Signed-off-by: Slávek Banko <slavek.banko@axis.cz>